(Not Applicable)
The field of invention is labels, more particularly a label having a protective cavity and method of manufacture.
RFID devices are known in the art, such as disclosed in U.S. Pat. No. 5,347,263. These devices are used in systems for access control, animal feeding and health programs, inventory control, process control, and security applications.
A typical RFID system has a passive RFID label having circuitry therein and a separate RFID reader/writer. The RFID reader/writer energizes the RFID label circuitry by transmitting a power signal. The power signal may convey data which is stored in memory incorporated in the RFID label circuitry. In response to the power signal the RFID label circuitry may transmit a response signal containing data stored in its memory. The RFID reader/writer receives the response signal and interprets the data contained therein. The data is then transmitted to a host computer for processing.
In order to minimize the cost of labels, the labels are fabricated in large quantities. One particular method of making the RFID label is to fabricate an RFID inlay by printing a conductive material, such as silver conductive ink, in a pattern defining multiple antennae, onto a substrate. The ink may be printed using silk screening techniques, such as in a sheet fed or roll operation. Once the antennae are printed, each antenna is die cut into individual inlays. Each inlay is placed in a carrier where an integrated circuit (IC) chip, such as a flip chip, is electrically connected to the antenna using conventional chip attachment methods. The chip is then encapsulated in an epoxy material and the entire assembly is sandwiched between protective layers.
This particular method of making an RFID label has several drawbacks. The inlay substrate material is expensive and when die cut, there is significant waste. Once the individual antennae are die cut into individual inlays, each inlay must be loaded into a carrier for subsequent processing. If a window is not cut into the inlay substrate, when the chip is encapsulated, there is a bump on the label which can result in the chip being easily ripped off of the label, or crushed, rendering the label inoperative. Finally, the bump on the chip makes putting the label through marking equipment, such as thermal transfer, ink jet, or laser printers, difficult.
Another method of manufacturing an RFID label, described in U.S. Pat. 5,528,222, has an antenna formed as an integral part of an insulating substrate and a circuit chip mounted on the substrate. This particular label requires an inlay substrate which significantly increases the label thickness and the overall cost of the label. To minimize the label thickness, a window may be cut in the inlay substrate allowing insertion of the chip into the window. Cutting a window in the substrate, however, further increases the cost of the label. Therefore, a need exists for a label which does not require cutting a window in the inlay substrate to minimize the bump.
The present invention provides a label having a protective cavity and a method for making the label. The label includes an inlay including a conductive material. A sheet is fixed over at least a portion of the inlay, and has a first surface and a second surface. A protective material is fixed to the first surface of the sheet, and an aperture extending through the protective material and sheet is positioned over at least a portion of the conductive material to define a protective cavity. A device is disposed in the protective cavity, and electrically connected to the conductive material, wherein the protective cavity surrounds the device. In another aspect of the present invention, the protective material is expandable from an unexpanded height to an expanded height, and the expanded height is at least 10% greater than the unexpanded height.
A general objective of the invention is to provide a label which is easy and economical to manufacture. The label can be formed by depositing a protective material onto a sheet, forming an aperture in the protective material and sheet, and then fixing the sheet over an inlay to form a protective cavity over the inlay. The label is easily formed using known methods and equipment to economically and easily manufacture the label.
Another objective of the present invention is to provide a label having a device that does not form a bump on the label surface. This objective is accomplished by forming a cavity in the label for receiving the device. The cavity provides a receptacle for receiving the device and avoiding a bump on the label.
The foregoing and other objectives and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention.